Geological Survey of Canada Current Research 2000-A18 Stratigraphic linkage of carbonate-rich units across east-central Vernon map area, British Columbia: are Kingfisher (Colby) and Big Ledge zinc-lead occurrences part of the same regional marker succession? R.I. Thompson and K.L. Daughtry 2000 ©Her Majesty the Queen in Right of Canada, 2000 Catalogue No. M44-2000/A18E-IN ISBN 0-660-18010-3 A copy of this publication is also available for reference by depository libraries across Canada through access to the Depository Services Program's website at http://dsp-psd.pwgsc.gc.ca A free digital download of this publication is available from the Geological Survey of Canada Bookstore web site: http://gsc.nrcan.gc.ca/bookstore/ Click on Free Download. All requests for permission to reproduce this work, in whole or in part, for purposes of commercial use, resale or redistribution shall be addressed to: Geoscience Information Division, Room 200, 601 Booth Street, Ottawa, Ontario K1A 0E8. Authors’ addresses Robert I. Thompson ([email protected]) GSC Pacific (Vancouver) 101-605 Robson Street Vancouver, British Columbia V6B 5J3 Kenneth L. Daughtry ([email protected]) Discovery Consultants P.O. Box 933 Vernon, British Columbia V1T 6M8 Stratigraphic linkage of carbonate-rich units across east-central Vernon map area, British Columbia: are Kingfisher (Colby) and Big Ledge zinc-lead occurrences part of the same regional marker succession?1 R.I. Thompson and K.L. Daughtry GSC Pacific, Vancouver Thompson, R.I. and Daughtry, K.L., 2000: Stratigraphic linkage of carbonate-rich units across east-central Vernon map area, British Columbia: are Kingfisher (Colby) and Big Ledge zinc-lead occurrences part of the same regional marker unit?; Geological Survey of Canada, Current Research 2000-A18, 5 p. (online; http://www.nrcan.gc.ca/gsc/bookstore) Abstract: A calcareous quartzite and calc-silicate marker succession can be mapped across east-central Vernon map area (82 L/7). Both the lithologies present and the trend of the succession suggest it correlates with host strata to the Kingfisher (Colby) and Big Ledge base-metal occurrences. This model expands potential exploration targets by defining a large region of potential host rocks that appear to extend from the eastern shores of Upper Arrow Lake west to the town of Chase, a distance of more than 100 km. Résumé : Une succession repère de quartzite calcareux et de roches calco-silicatées peut être suivie à travers la partie centre est de la région cartographique de Vernon (SNRC 82 L/7). Aussi bien les lithologies que l’orientation de la succession laissent croire à une corrélation avec les roches encaissantes des indices de métaux communs de Kingfisher (Colby) et de Big Ledge. Ceci accroît le nombre de cibles d’exploration potentielles en délimitant une vaste région de lithologies favorables qui semblent s’étendre vers l’ouest depuis la rive est du lac Arrow supérieur jusqu’à la ville de Chase, soit sur une distance de plus de 100 km. 1 Contribution to the Ancient Pacific Margin NATMAP Project 1 Current Research 2000-A18 INTRODUCTION quartzite, marble, and calc-silicate gneiss succession that underlies nearly all of east-central Vernon map area (Hoy, Fieldwork in 1999 focused on east-central Vernon map area 1976a, b). In this paper we pursue the idea that the succes- (82 L/7) between Trinity Valley on the west, Sugar Lake on sions that host these two zinc-lead occurrences are physically the east, Blue Springs Valley and Shuswap River on the linked; and that the exploration potential of the intervening south, and Trinity Hills and Park Range on the north (Fig. 1). area, in this case map area 82 L/7, is significant. The purpose of this work was to search out and map marker units in the high-grade Neoproterozoic and Paleozoic schist and gneiss succession, and to map the east-west extent of SUMMARY OF STRATIGRAPHIC overlying Triassic Slocan Group strata. RELATIONS Relevance of the work bears directly on an assessment of The area between the Okanagan Valley and the peaks that the zinc-lead and lead potential of the high-grade metamor- form the Monashee Mountains is underlain by a high-grade phic assemblages. Carbonate-hosted zinc occurrences called metamorphic succession dominated by quartzofeldspathic Big Ledge and Kingfisher (Fig. 1) occur within specific, car- biotite schist and paragneiss with lesser amounts of quartzite, bonate-dominated portions of the schist, paragneiss, marble, and amphibolitic schist, which, until now, have not Mara Kingfisher Lake Upper Arrow Greenbush Lake Ck. Lake 50° ¢ 45 N Kingfisher Zn-Pb occurrence Creek P ingsto River n Tsuias C River reek e Shuswap Shuswap Mabel Lak Ck. Ledge Creek 50° Sowsap 30¢ N 82 L/7 Big Ledge Zn-Pb Latewhos Nor Park Mtn. th occurrence Trinity Ck. Ck. Fasthall Sugar Ck. Christian Ireland Ck. Lake Ck. Ck. Sitkum (Trinity Fasthall Creek South Ck. area) Outlet (Mabel (Silver Hills Ck. Lake area) Ck. area) (Vidler Cusson Ck. Bessette Ridge Shus area) wap River ings Valley 50° Blue Spr Cherry Ridge 15¢ N 0 10 km 119°00¢ W 118°30¢ W 118°00¢W Figure 1. Generalized map of eastern Vernon map area (82 L) showing locations of the Big Ledge and Kingfisher zinc-lead occurrences. Inset map area (82 L/7) shows distribution of the calcareous quartzite marker unit highlighted by a stippled pattern; distribution of the marker unit in the Vidler Ridge area is taken from Carr (1990). 2 R.I. Thompson and K.L. Daughtry been systematically subdivided into mappable subunits, save outcrops of this unit may be visible among the trees as mas- rare carbonate markers recognized by Jones (1959). A sepa- sive, white- to light-grey-weathering cliffs that are often dif- rate, mappable overlying unit belonging to the Upper Triassic ficult to distinguish from white-weathering granite. Slocan Group consists of carbonaceous mudstone and lime- stone, siltstone, incidental sandstone, and volcanic rocks There are three main outcrop areas of the calcareous quartzite marker unit (Fig. 1): one in the highland area including both pyroclastic and epiclastic varieties. Neither between Trinity Valley and Shuswap River south of Christian Permian volcanic and carbonate rocks belonging to the Creek, referred to as the Trinity Creek area; another that par- Harper Ranch Group, nor (?)older carbonaceous schist, mar- allels the east margin of Mabel Lake and the Shuswap River, ble, and conglomerate belonging to the Spa Creek assem- referred to as the Mabel Lake area; and a third constitutes blage were recognized in the region mapped (82 L/7), much of the Silver Hills region, referred to as the Silver Hills possible evidence that the base of the Triassic Slocan Group area. The unit has been traced into cliffs south of Sugar Lake cuts stratigraphically down to the east and north. that bound the northwestern margin of Cherry Ridge, but its In the Monashee Mountains, where exposure is excep- extent there has not been determined. tional, high-grade schist and gneiss units have been subdi- In the Trinity Creek area, the calcareous quartzite marker vided into two fundamental and tectonically separate unit forms a shallow east-dipping homocline beneath Upper successions: 1) the Monashee Complex or ‘core zone’, a Triassic Slocan Group siltstone, argillite, and volcaniclastic window of paragneiss (layered biotite-quartz-feldspar rocks. Basal contact of the marker with underlying gneiss) and orthogneiss (gneissic biotite granodiorite, quartz quartzofeldspathic biotite schist was not observed. Contact monzonite, and veined hornblende-biotite granodiorite); and relations are partly obscured by a foliated granodiorite intru 2) a mantling zone of paragneiss and schist interpreted as an - sion thought to be Jurassic. There is little lithological varia east-verging allochthon (Brown et al., 1992) that contains a - tion within the unit, save the uppermost 10 to 20 m, which plethora of map units (Reesor and Moore, 1971; Read, 1979; consists of flaggy, muscovite-bearing, tan quartzite. Contact Carr, 1990) consisting for the most part of quartzite, marble, with the overlying carbonaceous siltstone and volcaniclastic amphibolite, and varieties of schist and paragneiss. It is rea- rocks of the Slocan Group is sharp to within a few metres; sonable to expect that some of these marker units extend however, the actual contact surface was not observed. westward into the region of dense vegetation that mantles the map area reported on here. Exposures in the Trinity Creek area are separated from those in the Mabel Lake area by a steeply dipping, Of particular importance is a calcareous quartzite/ west-side-down normal fault having displacement on the calc-silicate gneiss/marble marker unit that hosts the Big order of 1 km or less. In the Mabel Lake area, the marker unit Ledge zinc and lead mineralization (Hoy, 1976b; Fig. 1). is broadly folded about east-west-trending axes such that Similarities between it and a calcareous quartzite marker unit shallowly dipping fold limbs are discontinuously exposed having extensive distribution in map area 82 L/7 suggest along west-facing slopes (Fig. 1). A prominent north-dipping there may be considerable additional exploration potential rib can be traced from Bigg Creek south toward Christian concealed beneath the vegetated slopes and highlands. Lake. Unlike the Trinity Creek area, the calcareous quartzite Similarly we speculate that the calcareous quartzite marker unit here contains at least one unit of noncalcareous marker unit mapped throughout map area 82 L/7 is the same micaceous quartzite roughly 10 to 15 m thick. The marker succession that hosts the Kingfisher zinc-lead deposit, which unit is underlain by micaceous quartzite containing local sili- is contained in marble, quartzite, and calc-silicate gneiss ceous marble layers; systematic, foliation-parallel variations (Hoy, 1976a).